This interesting circuit, found in an old American publication, measures alternating signals in a frequency range from 100 Hz to 500 Hz. The operational amplifier is not common today, and a CA3140, for example, can be used instead. In this case, the power supply may be lower, with voltages from 6 to 12 V. The source must be symmetrical, and the bridge diodes can be 1N4148. The accuracy of the measurements will depend on the input resistors.
| Clique na imagem para ampliar |
